For more than a century, the Earnest C. Watson Lectures have been Caltech’s gift to its neighbors: free evenings in Beckman Auditorium where the institute’s researchers explain, in plain language, what they’re discovering. The 2026–27 season opened Wednesday night with Katie Bouman on using physics and AI to image the hidden universe — and demand is not the series’ problem. Advance registration for Bouman’s talk filled in less than 24 hours.
Next up, December 2: trust your gut
The season continues Wednesday, December 2, with microbiologist Sarkis Mazmanian and “Trust Your Gut: Microbiome Influences on Brain Health and Disease.” Mazmanian — Caltech’s Luis B. and Nelly Soux Professor of Microbiology and Merkin Institute Professor — studies the trillions of microbes in the human gut and their surprising influence on the brain, including in neurodegenerative diseases such as Parkinson’s. His lab’s work has helped turn the gut–brain connection from a fringe idea into one of the liveliest fields in medicine.
Advance registration for December 2 is already full, but the evening is still open to you. The preshow starts at 6 p.m. — food, drinks and books for purchase, music and interactive displays — and requires no registration at all. Doors open at 7 p.m., and unregistered guests can join the standby line; Caltech recommends being in it by 6:50 p.m. The talk and Q&A run 7:30 to 8:30 p.m., with conversation and concessions after. If you can’t get in, a recording will be posted afterward on Caltech’s YouTube channel.
One scheduling note if Mazmanian’s topic catches your interest: he is also the keynote speaker at the Caltech Entrepreneurs Forum’s “Microbiome Connection to Aging” session on Saturday, November 14, where the same science gets the startup-and-investors treatment.
How the Watsons work now
All Watson Lectures are free and open to the public, held in Beckman Auditorium on the Caltech campus. Registration now opens six weeks before each lecture — and, as the Bouman sellout showed, the popular ones go fast. Caltech offers email reminders when registration opens for each talk; sign up through the Watson Lectures page at caltech.edu.
The rest of the season
Wednesday, January 27, 2027 — Linda Spilker. JPL’s Spilker, a veteran of the Voyager and Cassini missions, explores interstellar space and the solar system. Registration opens December 16, 2026.
Wednesday, February 24, 2027 — Woody Fischer. Earth science, climate and geobiology — how life acquired carbon, and what that means for predicting global change.
Wednesday, March 17, 2027 — Charles Sprenger. Economics and decision-making: how humans actually choose.
Wednesday, April 7, 2027 — David Conlon. Beautiful mathematical patterns.
Wednesday, April 28, 2027 — Lulu Qian. Synthetic biology and molecular machines with rudimentary intelligence, built from DNA.
Wednesday, May 19, 2027 — Sujit Datta. Microbial behavior and biophysics — spying on microbes in hidden worlds.
Pasadena is lucky: some of the best science communication in the country happens a mile from Old Town, in a round white hall, for free. Just register early.
Sources: Caltech Events — the Watson Lectures series page and lecture listings (events.caltech.edu); Caltech Events newsletter, November 2026.
